Add test suite, coverage, keybind refactor, and repo cleanup

[joefarrelly]

Summary

• 47 pytest tests covering LuaParser, IsSessionUser, keybind builder helpers, and key view behaviours — all passing, 52% coverage
• pytest-cov wired with --cov-report=term-missing + XML; CI job uploads to Codecov
• Extract keybind logic from views.py into libs/keybind_builder.py (build_all_keybinds, build_single_keybinds, tier_sort_key) — pure functions now live in libs/ where they belong
• backend/test_settings.py overrides DB → SQLite in-memory and cache → locmem so tests need no running services
• CI: lint.yml renamed to "Lint and Test"; adds a test job (Python 3.12, installs MySQL dev headers, runs pytest with all required env vars)
• Badges: Lint/Test, Codecov, and Ruff badges added to readme.md
• dump.txt removed — contained real personal WoW data committed to git; now gitignored
• apicore/tests.py removed — superseded by tests/ package
• Stale DATA_PASSWORD env var row removed from readme.md

Test plan

• CI "Lint and Test" workflow passes on this PR (both lint and test jobs green)
• Codecov comment appears with coverage report

[gitguardian]

⚠️ GitGuardian has uncovered 1 secret following the scan of your pull request.

Please consider investigating the findings and remediating the incidents. Failure to do so may lead to compromising the associated services or software components.

🔎 Detected hardcoded secret in your pull request

GitGuardian id	GitGuardian status	Secret	Commit	Filename
34103880	Triggered	Generic Password	975fbe8	.github/workflows/lint.yml	View secret

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• install secret detection on pre-commit to catch secret before it leaves your machine and ease remediation.

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^{🦉 GitGuardian detects secrets in your source code to help developers and security teams secure the modern development process. You are seeing this because you or someone else with access to this repository has authorized GitGuardian to scan your pull request.}

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 52.88462% with 49 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
apicore/libs/keybind_builder.py	53.46%	47 Missing ⚠️
apicore/views.py	33.33%	2 Missing ⚠️

📢 Thoughts on this report? Let us know!